Increasing tropical cyclone intensity in the western North Pacific partly driven by warming Tibetan Plateau

The increase in intense tropical cyclone (TC) activity across the western North Pacific (WNP) has often been attributed to a warming ocean. However, it is essential to recognize that the tropical WNP region already boasts high temperatures, and a marginal increase in oceanic warmth due to global warming does not exert a significant impact on the potential for TCs to intensify. Here we report that the weakened vertical wind shear is the primary driver behind the escalating trend in TC intensity within the summer monsoon trough of the tropical WNP, while local ocean surface and subsurface thermodynamic factors play a minor role. Through observational diagnoses and numerical simulations, we establish that this weakening of the vertical wind shear is very likely due to the increase in temperature of the Tibetan Plateau. With further warming of the Tibetan Plateau under the Representative Concentration Pathway 4.5 scenario, the projected TCs will likely become stronger.

In general, I find this study to be persuasive; however, there is significant room for improvement in terms of scienfific wrifing and the quality of figures.In addifion, I do have reservafions about the structure of this manuscript.There are a large number of supplemental figures (15), which is almost five fimes the total figures included in the main manuscript text (3 main +1 schemafic).Moreover, these supplemental figures are referred to in both the results and methodology of this manuscript and seem more integral to the manuscript than just being included as supplemental material.My comments sorted by major and specific are below.(Please refer to supplementary material for the equafions) Major Comments: 1) Some of the wrifings are rather confusing.For example, what is "an unstable relafionship between TC intensity and sea surface temperature (Line 70)"?In your correlafion analysis porfion, why you stated, "interdecadal component is the three-year running mean" (Table S1)?The interdecadal fimescale refers to a fime period or phenomenon that spans mulfiple decades.It focuses on changes or variafions occurring over a period of approximately 10 to 30 years.The three-year temporal window is apparently too short.Similarly, "interannual component is without the linear trend," this is also wrong.Authors can simply call it detrended correlafion.
2) Lots of inconsistencies in the Figure plots, and the quality of the plot are generally poor.For example, the authors used black vectors in Figure 2, but changed them to blue in Figure 3; the "+" sign denotes the area that passed the significance test in the majority of Figures but denotes the area that DID NOT pass the significance test in Figure S15; In Figure 2b, "+" signs are overlaid by the black vectors and very hard to see them clearly.Why did you change to the "×" sign in Figure 2c?I suggest authors replot the Figures made by GrADS with the same standard and befter quality.
3) There are a number of instances where this reviewer would have preferred to structurally include the supplemental figures as regular figures in the text.For example, Supplemental figures 1 and 2 are nice introductory figures about the WNP MT.Why they are considered supplementary when they provide essenfial background informafion provided in lines 71-88?Specific Comments: 1.The descripfion of entropy deficit is inaccurate: Line 122 (and also Lines 431-433) "The energy from the ocean represented by entropy deficit (reflecfing the moist stafic energy from the underlying ocean; see Methods)".According to Tang and Emanuel (2012), a non-dimensional entropy deficit can be wriften as: where Sm* is the saturafion entropy at 600 hPa in the inner core of the TC, Sm is the environmental entropy at 600 hPa, SSST* is the saturafion entropy at the sea surface temperature, and Sb is the entropy of the boundary layer.The numerator is the difference in entropy between the TC and the environment at 600hPa, while the denominator is the air-sea disequilibrium.Therefore, a phrase like "entropy deficit at 600 hPa (Line 431)" and "entropy deficit between ocean and atmosphere (Line 431-432)," is misleading and not appropriate.Do you simply refer to the entropy difference?
Equafion ( 6) is also quesfionable.Based on Tang and Emanuel (2012), moist entropy can be wriften as , why entropy deficit (unit in J/kg/K) can be wriften into CAPE (unit in J/kg) form?The authors cite Bister and Emanuel (2002) here, but I found no relevant equafions in this paper.
2. Lines 339-343: Authors claimed: "Because the CCSM3 model can well capture….,CMIP5 CCSM4 … are used".This does not make sense.CCSM4 is the successor to CCSM3, but does it sfill work well in the East Asian-WNP region?Both CCSM3 and CCSM4 ARE NOT in the Gaussian grids!CAM4 uses finite volume dycore, while Gaussian grids data are typically output from Spectral dycore model like ECMWF IFS.S15d: Panel (d) is apparently very different from panel (c), how can you say "As in (c)"?"temporal curve" is confusing, do you simply mean "fimeseries"?Indeed, I am very confused with Figure S15d, is this seasonal mean TC lifefime averaged (or lifefime peak intensity) minimum sea level pressure simulated by RegCM4 during 1986-2050?If so, how did authors idenfify and track TCs?How many simulated TCs in this area every year?Is it comparable to the observafion?Why did you plot TC minimum sea level pressure while the rest of the paper uses 10-m wind speed?A phrase like "minimum sea level pressure (hPa) around the TC center" is very awkward, should be "TC minimum sea level pressure (hPa)".Line 515 "significant decrease of 1.6 hPa" is too vague.Is this the difference between the 2022-2050 mean and the 1986-2005 mean?Are you sure the 1.6hPa difference is significant?4. Line 302: "Projecfions imply a more frequent occurrence of intense typhoons," did authors find similar results in your RegCM4 downscaling analyses? 5. Line 329: "dotes" should be "dots".

Figure
6. Authors' definifion of OHC is not standard.What is T ̅ ?"mean temperature in a period" is again too vague.If authors refer the simply OHC, it can be wriften as If authors refer to tropical cyclone heat potenfial (TCHP), it can be wriften as 7. Line 417-418: Also need to input surface pressure.8. Line 536: Authors did not use ERA5 data in the analysis, at least did not state it in the paper.Why wrote ERA5 here?

Reviewer #2 (Remarks to the Author):
Recommendafion: Accept with revision.The regional TC intensificafion results linked to TP warming found by the authors are noteworthy and novel, and, if model projecfions are reliable, may be experienced even more in the future with further TP warming.(Note the caveat of the dependence of these results on the reliability of models for such regional details.)The authors establish that over the period 1988-2018 there is a rising trend in TC intensity in the monsoon trough region of the WNP basin, and a reducfion in verfical shear there, which seems to be the important driving factor, since local thermodynamic changes there (SST, PI, etc) are minimal or in the opposite direcfion needed for intensificafion.Through correlafions and then through some climate model experiments, they show that warming over the Tibetan Plateau region causes a remote atmospheric teleconnecfion that leads to reduced verfical windshear in the monsoon trough region.They further show that future climate warming scenarios by a climate model have further Tibetan Plateau warming and further reduced verfical wind shear in the MT region.In their methods, they report that a regional dynamical downscaling model based on these climate model simulafions produces increased TC intensifies in the monsoon trough region, but that effect is very small (only 1.6 hPa decrease in central pressure of TCs over the coming century).
In the manuscript, the authors are not claiming that the change in TC intensity, verfical shear, Tibetan warming, and so forth over 1988-2018 is a detectable anthropogenic change.
See my detailed comments below.
General comment: what caused TP warming (P1 to P2)?It seems that the authors are taking no strong posifion on this quesfion, but are nofing that a further TP warming is projected for the coming century, with some related impacts on VWS in the MT region.Perhaps that should state somewhere that the above quesfion, while important, is outside the scope of this study.Fig. 1b: why are the TC intensifies of the 3 datasets offset from each other?Line 80-81, does the SAH disappear and an anficyclone appear to the SW or does the anficylone feature (named SAH) shift to the southwest and get a new different name?
Line 137-138: suggest to say "...TC intensity is more closely linked to VWS than MPI or OHC in the MT region.Therefore, we infer that the JAS weakened VWS during the recent three decades is a dominant factor..." Line 164-165: based on Ref 37, I suggest to change this slightly to: "This result supports previous findings that WNP TCs develop more slowly when embedded within a monsoon gyre circulafion due several mechanisms, including inhibifing effects of verfical wind shear (36,37)." Line 172: delete "remarkably" here Line 172-186: I suggest the authors focus more on 200mb winds or vorficity as opposed to a parficular geopotenfial height contour when referring to the eastward shift.With general atmospheric warming throughout the tropical region (e.g., Fig. 2b), the geopotenfial heights for the 200mb level will be elevated in general (as apparent in Fig. S6e,f for example), making it harder to infer circulafion changes based on changes of individual Z200 contours on a map.So they could instead refer to Fig. 2b and Fig. S6B, or to the horizontal gradient features in the Z fields in Fig. Line 173-174: "The three-year running mean 600-hPa (close to the surface) geopotenfial height in the central-western TP (83-88oE, 29o-34oN) has a significant correlafion of 0.64 with TC intensity in the MT area (Table S1)..." This is the first place where the "TPH" index in Table S1 is defined.It needs to be defined in the Table S1 capfion.Also the correlafion of 0.64 is for interdecadal variafions.This seems to be the first place where "interdecadal variafions" is defined as three-year running mean.This needs to be made more clear in the text.
Fig. S7c,d should be plofted over the same lafitude range to make comparison between them easier.Line 190-197.I don't find this discussion and interpretafion of the results shown in the figures to be enfirely convincing.As an example, there is an "A" label for anficyclone on the map for Fig. 2c, but this is a very weak feature.The verfical velocity "wavetrain" from Fig. S8 seems a liftle more convincing.I recommend delefing some of the weaker material here (lines 194-197).
Line 198-200.Are the authors proposing a mechanism here?This seems to be referring some form of natural internal variability (Asian-Pacific Oscillafion).I suggest to either elaborate or delete this sentence.
Line 219: You could say "remarkable" instead of "remarkably" Lines 219-222: This sentence makes no sense.What does the TC intensity trend have to do with the removal of a linear trend in TP surface pressure?Rewrite to clarify or delete.
Line 228: "To expore the hypothesis..." Line 241-242: It is hard to discern the "southward cyclonic anomaly in the lower troposphere" where the "C" is labelled in Fig. 3c.It seems from this and my earlier comment on the "A" feature in Fig. 2c that the authors are trying to stretch to find a correspondence of circulafion features between the observafions and the TP heafing experiments in the MT region and nearby regions.I don't find the resulfing discussion to be that convincing on those features.
Line 380-387: Are the authors making the claim that the trends over 1988-2018 are outside of expected natural variability, and if so, what is the basis for this claim?They could test the variafions against variafions in climate model control runs to see how unusual they are compared to control run variability.(This could not be done for TC intensity but for some of the other environmental changes such as TP warming).
Perhaps the authors are not making any claims about past trends being outside of natural variability.I realize their linkage to anthropogenic climate change is mostly through the use of future projecfions showing further warming of the TP region and future VWS reducfion over the MT region.
Line 483-485: How are the warming Asia and warming Europe experiments constructed?Line 515-516: A 1.6 hPa decrease in minimum sea level pressure around the TC center in the future scenario (here I assume the authors mean some composite TCs from the future and historical runs) seems like a finy change for a full century of warming.Is it of any pracfical importance?Or have I misinterpreted?

Reviewer #3 (Remarks to the Author):
The thesis of this ms.Is that the recent upward trend in strong tropical cyclones in the West Pacific is the result of weakening verfical wind shear, and that in turn is a response to warming of the Tibetan plateau.The argument rests on analyses of observed meteorological data, and numerical simulafions.Overall, I would say the case is plausible, if not overwhelmingly convincing.If the argument can be fightened by more careful discussion, the ms.may be suitable for publicafion.
First, a presentafional issue: there are many figures, of which 9 (out of 13 total) are labelled as "supplementary."It is, in fact, quite impossible to follow the main body of the text, containing the key arguments of the paper, without reference to the supplementary figures, leaving one to wonder in what sense they are "supplementary."Jumping back and forth between the supposedly important figures and the supplementary ones can be very irritafing to the reader (it certainly was to this reviewer).Scienfific issues, in the order they arise: (164-165): This sentence is a non sequitur -it is not jusfified by anything that precedes it in this paragraph.
(177-183): These sentences are not supported by the arguments presented.First, the statement about anomalous upward mofion east of the strengthened South Asian High has no basis.It rests on eq. ( 8) in line 445, which, as the text states, applies only in the cyclonic or anficyclonic centers where vorficity advecfion is negligible: meaning that it cannot be applied "east of the high."The rest of the argument, that this leads to increased precipitafion, anomalous heafing, and a consequent upper level anficyclonic anomaly, is not very convincing.
(210-211): This sentence is really a non sequitur.Upward transfer of wave acfivity (not energy) in no way implies thermal forcing.Any low-level forcing would have the same result.
In general, the results of the model simulafions are more convincing than the analysis of observafions.In general, I find this study to be persuasive; however, there is significant room for improvement in terms of scientific writing and the quality of figures.In addition, I do have reservations about the structure of this manuscript.There are a large number of supplemental figures (15), which is almost five times the total figures included in the main manuscript text (3 main +1 schematic).Moreover, these supplemental figures are referred to in both the results and methodology of this manuscript and seem more integral to the manuscript than just being included as supplemental material.Answer: We have made substantial revisions to the manuscript, encompassing improvements in writing, figures, overall structure, and content.We also introduce some statements in Methods to the text and some of supplementary figures to the regular ones, which reduce the length in Methods and the number of supplementary figures.

Major Comments
Question 1) Some of the writings are rather confusing.For example, what is "an unstable relationship between TC intensity and sea surface temperature (Line 70)"?In your correlation analysis portion, why you stated, "interdecadal component is the three-year running mean" (Table S1)?The interdecadal timescale refers to a time period or phenomenon that spans multiple decades.
It focuses on changes or variations occurring over a period of approximately 10 to 30 years.The three-year temporal window is apparently too short.Similarly, "interannual component is without the linear trend," this is also wrong.Authors can simply call it detrended correlation.

Answer:
(1) About "what is "an unstable relationship between TC intensity and sea surface temperature": Before the cessation of aircraft reconnaissance, the adjusted TC power dissipation index estimate exhibits a strong correlation with SST.However, post-1988, this correlation weakens considerably.Moreover, a few studies have reported a high correlation between the Atlantic Multidecadal Oscillation and TC intensity in the WNP from 1950 to 201829-30.But this strong correlation has notably diminished after 1987.Thus, the inhomogeneity of TC intensity data due to the halt in aircraft reconnaissance in 1988 may lead to an unstable relationship between TC intensity and SST.We have added some statements in lines 72-81.More detailed statements are given in Methods ( 2).
(2) In line with Li and Chakraborty (2020), who applied a 3-year smoothing technique to TC and other time series, we have similarly smoothed all the time series to minimize the impact of short-term climatic factors.We have updated the terminology by replacing "interdecadal component" with "the smoothed series" and "interannual component" with "detrended component." Question 2) Lots of inconsistencies in the Figure plots, and the quality of the plot are generally poor.
For example, the authors used black vectors in Figure 2, but changed them to blue in Figure 3; the "+" sign denotes the area that passed the significance test in the majority of Figures but denotes the Answer: According the suggestions, we have made improvements to the figures and have ensured their consistent presentation throughout the manuscript.
Question 3) There are a number of instances where this reviewer would have preferred to structurally include the supplemental figures as regular figures in the text.For example, Supplemental figures 1 and 2 are nice introductory figures about the WNP MT.Why they are considered supplementary when they provide essential background information provided in lines 71-88?
Answer: We have added some of supplemental figures to the regular ones.

Specific Comments
Question 1.The description of entropy deficit is inaccurate: Line 122 (and also Lines 431-433) "The energy from the ocean represented by entropy deficit (reflecting the moist static energy from the underlying ocean; see Methods)".According to Tang and Emanuel (2012), a non-dimensional entropy deficit can be written as: where Sm* is the saturation entropy at 600 hPa in the inner core of the TC, Sm is the environmental entropy at 600 hPa, SSST* is the saturation entropy at the sea surface temperature, and Sb is the entropy of the boundary layer.The numerator is the difference in entropy between the TC and the environment at 600hPa, while the denominator is the air-sea disequilibrium.Therefore, a phrase like "entropy deficit at 600 hPa (Line 431)" and "entropy deficit between ocean and atmosphere (Line 431-432)," is misleading and not appropriate.Do you simply refer to the entropy difference?Equation ( 6) is also questionable.Based on Tang and Emanuel (2012), moist entropy can be written as , why entropy deficit (unit in J/kg/K) can be written into CAPE (unit in J/kg) form?The authors cite Bister and Emanuel (2002) here, but I found no relevant equations in this paper.
Answer: Thank you for your explanation.We now have a better understanding of the calculations related to entropy deficit.In light of this, we remove the calculation of entropy deficit from the manuscript because a variable similar to entropy deficit (CAPE*-CAPE) is included in MPI and this paper considers variables such as MPI, OHC, and SST.This removal of entropy deficit does not affect our results about the connection between ocean and TC."As in (c)"?"temporal curve" is confusing, do you simply mean "timeseries"?Indeed, I am very confused with Figure S15d, is this seasonal mean TC lifetime averaged (or lifetime peak intensity) minimum sea level pressure simulated by RegCM4 during 1986-2050?If so, how did authors identify and track TCs?How many simulated TCs in this area every year?Is it comparable to the observation?Why did you plot TC minimum sea level pressure while the rest of the paper uses 10m wind speed?A phrase like "minimum sea level pressure (hPa) around the TC center" is very awkward, should be "TC minimum sea level pressure (hPa)".Line 515 "significant decrease of 1.6 hPa" is too vague.Is this the difference between the 2022-2050 mean and the 1986-2005 mean?Are you sure the 1.6hPa difference is significant?Answer: We have revised the related statements of Fig. S15d in the old version (now in Fig. S8c).Regarding the identification and tracking of simulated TCs, we employed the TSTORMS (Detection and Diagnosis of Tropical Storms in High-Resolution Atmospheric Models) software (www.gfdl.noaa.gov/tstorms/) in our simulations.The detailed statements are seen in lines 496-505.
In our model, the mean annual total number of TCs during 1986-2005 is 9 yr -1 , which is less than that observed (20 yr -1 ).This model underestimation is likely due to the coarse horizontal resolution in our simulation, consistent with previous reports by Jin et al. (2016) and Torres-Alavez et al. (2021).However, since our primary interest is in the changes in TCs, the TC number issue might become less critical as it affects both present and future cyclones.These related statements have been added (lines 506-508).
Answer: In this revision, according to your suggestion, we have updated the definition of OHC (Song et al., 2020).

= − 26 ∆
Using this revised definition, we obtained consistent results, with no changes in the correlation between TC and OHC.Please refer to lines 143, 145, and 409-415 and Table S1.
Reference: Song, J., Duan, Y., and Klotzbach, P., ( 2020 Answer: It is due to our mistake.We have deleted it. Recommendation: Accept with revision.The regional TC intensification results linked to TP warming found by the authors are noteworthy and novel, and, if model projections are reliable, may be experienced even more in the future with further TP warming.(Note the caveat of the dependence of these results on the reliability of models for such regional details.)The authors establish that over the period 1988-2018 there is a rising trend in TC intensity in the monsoon trough region of the WNP basin, and a reduction in vertical shear there, which seems to be the important driving factor, since local thermodynamic changes there (SST, PI, etc) are minimal or in the opposite direction needed for intensification.Through correlations and then through some climate model experiments, they show that warming over the Tibetan Plateau region causes a remote atmospheric teleconnection that leads to reduced vertical windshear in the monsoon trough region.They further show that future climate warming scenarios by a climate model have further Tibetan Plateau warming and further reduced vertical wind shear in the MT region.In their methods, they report that a regional dynamical downscaling model based on these climate model simulations produces increased TC intensities in the monsoon trough region, but that effect is very small (only 1.6 hPa decrease in central pressure of TCs over the coming century).
In the manuscript, the authors are not claiming that the change in TC intensity, vertical shear, Tibetan warming, and so forth over 1988-2018 is a detectable anthropogenic change.
See my detailed comments below.
General comment: what caused TP warming (P1 to P2)?It seems that the authors are taking no strong position on this question, but are noting that a further TP warming is projected for the coming century, with some related impacts on VWS in the MT region.Perhaps that should state somewhere that the above question, while important, is outside the scope of this study.
Answer: Previous studies have conducted the attribution analysis of the TP warming over the past decades (covering our study period).It is found that this warming is almost dominated by anthropogenic influence.The trends of SAT during 1985-2014 in all seasons are positive over the TP, and the observed warming amplification during 1961-2014 is attributed to anthropogenic influence.The attributable contribution from anthropogenic influence is estimated to be much larger than that from natural signal for most warming events in the TP.The associated statements are in lines 302-312.Question 7. Line 173-174: "The three-year running mean 600-hPa (close to the surface) geopotential height in the central-western TP (83-88oE, 29o-34oN) has a significant correlation of 0.64 with TC intensity in the MT area (Table S1)..." This is the first place where the "TPH" index in Table S1 is defined.It needs to be defined in the Table S1 caption.Also the correlation of 0.64 is for interdecadal variations.This seems to be the first place where "interdecadal variations" is defined as three-year running mean.This needs to be made more clear in the text.

Answer:
We add the related statement and replace 600-hPa (close to the surface) geopotential height with surface pressure (lines 188-189).This change does not affect the result.
Question 8. Fig. S7c,d should be plotted over the same latitude range to make comparison between them easier.
Question 9. Line 190-197.I don't find this discussion and interpretation of the results shown in the figures to be entirely convincing.As an example, there is an "A" label for anticyclone on the map for Fig. 2c, but this is a very weak feature.The vertical velocity "wavetrain" from Fig. S8 seems a little more convincing.I recommend deleting some of the weaker material here (lines 194-197).
Answer: According to your suggestion, we have deleted the related statements.
Question 10.Are the authors proposing a mechanism here?This seems to be referring some form of natural internal variability (Asian-Pacific Oscillation).I suggest to either elaborate or delete this sentence.
Answer: According to your suggestion, we have deleted the relate statements.
Question 12. Lines 219-222: This sentence makes no sense.What does the TC intensity trend have to do with the removal of a linear trend in TP surface pressure?Rewrite to clarify or delete.

Answer:
We have deleted the relate statements.
Question 14. Line 241-242: It is hard to discern the "southward cyclonic anomaly in the lower troposphere" where the "C" is labeled in Fig. 3c.It seems from this and my earlier comment on the "A" feature in Fig. 2c that the authors are trying to stretch to find a correspondence of circulation features between the observations and the TP heating experiments in the MT region and nearby regions.I don't find the resulting discussion to be that convincing on those features.
Answer: Following your suggestion for the observation, we also deleted the relate statements for the simulations.

Answer:
We have made substantial revisions to the manuscript, introducing some statements in Methods to the text and some of supplementary figures to the regular ones, which reduce the length in Methods and the number of supplementary figures.It rests on eq. ( 8) in line 445, which, as the text states, applies only in the cyclonic or anticyclonic centers where vorticity advection is negligible: meaning that it cannot be applied "east of the high." The rest of the argument, that this leads to increased precipitation, anomalous heating, and a consequent upper level anticyclonic anomaly, is not very convincing.

Answer:
In this revision, we consider two terms of vorticity equation (not with ∝ − , that is, Eq. ( 8) of the old version) as follows.

∝ − • ∇ +
including the low-level dynamic and thermodynamic forcings.Our observed Fz feature (Fig. 4c) closely resembles the simulation driven by the TP surface heating (Fig. 5e).This similarity suggests that the upward transfer of wave activity could indeed be caused by thermal forcing.

Comment:
In general, the results of the model simulations are more convincing than the analysis of observations.

Answer:
In fact, we propose the hypothesis that a warming TP affects VWS in the MT area.
We first give the link between TP and VWS and the associated physical processes from observation, including upper-tropospheric atmospheric circulations, the eastward extensions of both SAH and temperature from the TP to the western North Pacific, and the meridional propagation of anomalous wave in the western North Pacific.Especially, we add the analysis for the eastward extension of SAH anomalies through advection temperature, vertical variation of vorticity, and upward motion.
Then, we rigorously validate this hypothesis and related intermediate processes through comparing the model results with the observations in detail.Our comparison shows the high similarity between the simulated and observed physical processes though the simulated positions are systematically northward.The similarity sufficiently demonstrates our hypothesis.
Figure 3 capfion (line 33).Why does the "(a)" appear in this descripfion of panel (b).Is this a typo?Also could you perhaps start the second sentence as: "(b-e) Differences between P2 and P1 in (b) VWS..." and use the inifial few words as the prefix for all of the panels (b-e)?Also rather than "represent the 95% level" you could say "represent stafisfically significant results at the p=0.05 level" and later on say "represent the p=0.05 level" (2 occurrences) Throughout manuscript: Change nomenclature from 95, 99, 99.9%, etc. level to significant (or stafisfically significant) at the p=0.05, p=0.01, or p=0.001 level.
Line 267-268: "A significant warming" (not "The significant warming" and "we conduct sensifivity ..." (drop "the") Line 281: "One might speculate that global paftern of SST change from P1 to P2 plays the dominant role in the weakened..." (this is needed to clarify that you are not performing an experiment with a globally uniform change of SST).Line 408-429: Although it is not likely to change any conclusions of this study (owing to the small influence of SST on TC intensity in the region relafive to verfical shear), you could menfion here and in the main paper the work of I-I Lin and collaborators looking at a version of MPI that includes ocean temperature averaged down to a certain depth (and their work on verfical profile of ocean temperature change and its influence on TC intensity.) Fig. S6 e,f for example to illustrate the eastward shift in circulafion associated with the SAH.Individual Z200 contours conflate general large scale warming with more local circulafion changes and need to be interpreted with caufion.
81): The SAH migrates south rather than disappears.(81-83): I have no idea what this sentence is supposed to mean.
Review of "The increasing tropical cyclone intensity in the western North Pacific monsoon trough controlled by warming Tibetan Plateau" by Xu et al.Summary: This study investigated the role of the Tibetan Plateau (TP) in the tropical cyclone (TC) intensity over the western North Pacific (WNP) monsoon trough (MT) area.They found that the recent increase trend of TC intensity in the WNP MT could be primarily attributed to the decreased vertical wind shear (VWS) due to the TP warming, while the contributions from the local/global ocean warming only played a minor role.In addition, the authors postulated that the WNP MT TC intensity would further increase in the future warmer climate.
area that DID NOT pass the significance test in FigureS15; In Figure2b, "+" signs are overlaid by the black vectors and very hard to see them clearly.Why did you change to the "×" sign in Figure2c?I suggest authors replot the Figures made by GrADS with the same standard and better quality.

Question 2 .
Lines 339-343: Authors claimed: "Because the CCSM3 model can well capture….,CMIP5 CCSM4 … are used".This does not make sense.CCSM4 is the successor to CCSM3, but does it still work well in the East Asian-WNP region?Both CCSM3 and CCSM4 ARE NOT in the Gaussian grids!CAM4 uses finite volume dycore, while Gaussian grids data are typically output from Spectral dycore model like ECMWF IFS.Answer: We have removed the statements "Because the CCSM3 model can well capture the observed atmospheric circulation changes in the East Asian-WNP region (including the tropical WNP VWS anomaly pattern)" and "Gaussian grids" from the manuscript (lines 350-351).Question 3. Figure S15d: Panel (d) is apparently very different from panel (c), how can you say

Question 1 .Question 2 .
Fig. 1b: why are the TC intensities of the 3 datasets offset from each other?Answer: In order to avoid the confusion, we have modified the presentation of the interquartile ranges of TC intensity from the three datasets.The previously overlapping ranges, indicated by shading, have been separated into distinct figures, as shown in Fig. 2b of this revised version.Line 80-81, does the SAH disappear and an anticyclone appear to the SW or does the anticyclone feature (named SAH) shift to the southwest and get a new different name?Answer: We have changed the statements (lines 93-94).Question 3. Line 137-138: suggest to say "...TC intensity is more closely linked to VWS than MPI or OHC in the MT region.Therefore, we infer that the JAS weakened VWS during the recent three decades is a dominant factor..." Answer: We have revised (lines 157-159).Question 4. Line 164-165: based on Ref 37, I suggest to change this slightly to: "This result supports previous findings that WNP TCs develop more slowly when embedded within a monsoon gyre circulation due several mechanisms, including inhibiting effects of vertical wind shear (36,37)."Answer: According to one reviewer's suggestion, we have deleted the related statement.Question 5. Line 172: delete "remarkably" here Answer: We have deleted.Question 6. Line 172-186: I suggest the authors focus more on 200mb winds or vorticity as opposed to a particular geopotential height contour when referring to the eastward shift.With general atmospheric warming throughout the tropical region (e.g., Fig. 2b), the geopotential heights for the 200mb level will be elevated in general (as apparent in Fig. S6e,f for example), making it harder to infer circulation changes based on changes of individual Z200 contours on a map.So they could instead refer to Fig. 2b and Fig. S6B, or to the horizontal gradient features in the Z fields in Fig. Fig.S6 e,f for example to illustrate the eastward shift in circulation associated with the SAH.Individual Z200 contours conflate general large scale warming with more local circulation changes and need to be interpreted with caution.Answer: According to your suggestion, we focus on 200 mb winds and consequently remove the geopotential height contours and the related figure.

Question 2 .
(80-81): The SAH migrates south rather than disappears.Answer: We have revised the statement (line 93-94).Question 3. (81-83): I have no idea what this sentence is supposed to mean.Answer: We have deleted the statement "Referring to the similarity of the lower-and uppertropospheric circulations in the MT area,".Question 4. (164-165): This sentence is a non sequitur -it is not justified by anything that precedes it in this paragraph.Answer: We have deleted the statement.Question 5. (177-183): These sentences are not supported by the arguments presented.First, the statement about anomalous upward motion east of the strengthened South Asian High has no basis.
Question 8. Line 536: Authors did not use ERA5 data in the analysis, at least did not state it in the paper.Why wrote ERA5 here?
Question 15.Line 380-387: Are the authors making the claim that the trends over 1988-2018 are outside of expected natural variability, and if so, what is the basis for this claim?They could test the variations against variations in climate model control runs to see how unusual they are compared to control run variability.(Thiscould not be done for TC intensity but for some of the other environmental changes such as TP warming).The thesis of this ms.Is that the recent upward trend in strong tropical cyclones in the West Pacific is the result of weakening vertical wind shear, and that in turn is a response to warming of the Tibetan plateau.The argument rests on analyses of observed meteorological data, and numerical simulations.Overall, I would say the case is plausible, if not overwhelmingly convincing.If the argument can be tightened by more careful discussion, the ms.may be suitable for publication.First, a presentational issue: there are many figures, of which 9 (out of 13 total) are labelled as "supplementary."It is, in fact, quite impossible to follow the main body of the text, containing the key arguments of the paper, without reference to the supplementary figures, leaving one to wonder in what sense they are "supplementary."Jumping back and forth between the supposedly important figures and the supplementary ones can be very irritating to the reader (it certainly was to this reviewer).